As the method of bleaching olefin sulfonates, a bleaching method employing hypochlorite is most popular, and the bleaching effect thereof is admittedly great. However, a bleaching method employing hypochlorite is attended with various troubles with respect to the bleaching treatment including sodium chloride is produced as a by-product at the time of bleaching, corrosion of the apparatus used for bleaching takes place, etc.
There is also known a bleaching method employing hydrogen peroxide as disclosed in British Pat. No. 983,056 as the bleaching agent for olefin sulfonates. But, this method is inferior in bleaching effect compared with the foregoing method employing hypochlorite, and a satisfactory bleaching effect cannot be attained when it is put to practical use.